The present invention relates to a method of driving a liquid crystal display panel which includes color filters and performs a color display, wherein the number of display colors is reduced and limited, and further, a driving signal is stopped to reduce the power consumption of the liquid crystal display panel, thereby enabling low power consumption. Further, the present invention relates to a method of controlling a display of a timepiece to which reduction in power consumption is strongly required, wherein a liquid crystal display panel thereof is driven by the above-described driving method.
As a method of driving a liquid crystal display panel including: signal electrodes provided on a first substrate; opposed electrodes provided on a second substrate; color filters provided on the first substrate or on the second substrate; and a liquid crystal layer sealed between the first substrate and the second substrate, and performing a color display by electro-optical change in the liquid crystal layer at pixel portions constituted of intersections of the signal electrodes and the opposed electrodes, a color display pattern signal of applying selection signals in a time sharing manner to all the signal electrodes which constitute the pixel portions of the liquid crystal display panel and applying data signals to the opposed electrodes in correspondence to the selection signals of the respective signal electrodes to thereby perform a display, is currently used in a small-sized information device.
One color display pattern signal uses a display pattern signal of applying gradation signals at many levels, and another uses a display pattern signal of applying gradation signals at several levels, and, further, a color display can be performed using a binary color display pattern signal using only ON/OFF. Even a case where gradation signals are not applied at levels but are applied at no levels are applied can also be regarded as gradation at many levels. That is because the no level gradation can be regarded as smooth gradation having a large number of gradation levels.
It should be noted that a full color display generally represents a display to which the gradation signals having no levels are applied as described above, but a display to which the gradation signals at many levels are applied is also called the full color display in this Description.
Further, d liquid crystal display panel of a liquid crystal display device having no color filter disposed has been developed, which has a display pattern signal of applying the gradation signals at many levels or the gradation signals at several levels, or of using only ON/OFF.
By the way, it is important for the liquid crystal display panel to have excellent display quality. In addition, as TVs shifted from a black-and-white display to a color display, the color display can provide variety in presentation of information.
On the other hand, as the display is shifted from a monochrome binary display to the gradation display at many levels, and further to the full color display, the frequency of a signal required for the display increases and an effective voltage applied to the liquid crystal layer decreases, bringing about a disadvantage that a voltage to be applied to each electrode needs to be increased.
Concerning the above, there is a method of applying signals to the signal electrodes after executing arithmetic processing to the signals for several rows of signal electrodes in order to reduce the voltages to be applied to the respective electrodes, but the arithmetic processing and a memory are necessary for the display, requiring further improvement to reduce power consumption.
Further, as a method of solving a decrease in display contrast due to a frame response phenomenon which occurs when using a high response super twisted nematic (STN) liquid crystal, a mode is suggested in SID92 Digest xe2x80x9cActive Addressing Method for High-Contrast Video-Rate STN Display.xe2x80x9d It is necessary to simultaneously apply voltages corresponding to orthogonal functions to row electrodes (signal electrodes) and to apply voltages corresponding to results of product-sum operations between display information of the respective columns and the functions provided to the respective row electrodes, to column electrodes (data electrodes), presenting disadvantages of occurrence of the arithmetic processing and the switching of signals to the data electrodes corresponding to the number of the row electrodes to which voltages are simultaneously applied, and occurrence of consumption of electric power due to charging and discharging currents of the liquid crystal.
Moreover, a cellular phone or the like employs a partial display of performing a display limited to a display such as an icon or the like during a reception stand-by state, which causes a disadvantage that the quantity of displayable information decreases.
Therefore, an object of the present invention is to reduce electric power consumed by a liquid crystal display device, which includes color filters and is capable of providing much information in a color display to a user thereof, to increase battery life with its display quality maintained as high as possible.
In particular, another object of the present invention is to enable realization of both the color display and low power consumption in the liquid crystal display device to enable a color display in a timepiece which has a strict limitation in volume and battery capacity.
To achieve the above-described objects, in the present invention, when in a color liquid crystal display panel including: a transparent first substrate formed with a plurality of signal electrodes and a transparent second substrate formed with a plurality of data electrodes arranged so that a face formed with the signal electrodes and a face formed with the data electrodes are opposed to each other; a liquid crystal layer sealed in a gap therebetween; pixel portions respectively constituted at portions where the signal electrodes cross over and planarly overlap the data electrodes; and color filters, in which filters of three primary colors are alternately arranged at least at positions corresponding to the pixel portions, provided on the first substrate or on the second substrate, a display is performed by selectively applying a voltage between the signal electrode and the opposed electrode to thereby change optical characteristics of the liquid crystal layer between the signal electrode and the opposed electrode at the pixel portion, the display is performed as follows.
A normal color display of applying selection signals to the plurality of signal electrodes constituting all the pixel portions of the color liquid crystal display panel in a time sharing manner, and applying data signals to the data electrodes in correspondence to the selection signals of the signal electrodes to allow the color filters of the pixel portions to be individually selected; and a color reducing display of applying selection signals in such a manner to simultaneously select a plurality of the signal electrodes to simultaneously select the filters of a plurality of the colors arranged at positions corresponding to the plurality of signal electrodes; are selectively performed.
Alternatively, a normal color display of applying selection signals to the plurality of signal electrodes constituting all the pixel portions of the color liquid crystal display panel in a time sharing manner, and applying data signals to the data electrodes in correspondence to the selection signals of the signal electrodes to allow the color filters of the pixel portions to be individually selected; and a limited color display of applying selection signals to part of the plurality of signal electrodes in a time sharing manner, and not applying selection signals to other signal electrodes to allow only the color filters arranged at positions corresponding to the signal electrodes to which the selection signals are applied to be selected; are selectively performed.
In this event, it is suitable that the driven color liquid crystal display panel is a color liquid crystal display panel including color filters, in which filters of three primary colors in the form of stripes are alternately arranged to be parallel to and planarly overlap the signal electrodes, provided on the first substrate or on the second substrate, and selection signals are applied to simultaneously select a plurality of the signal electrodes in the color reducing display to simultaneously select the filters of a plurality of the colors in the form of stripes arranged to planarly overlap the plurality of signal electrodes respectively.
Alternatively, it is suitable that selection signals are applied to part of the plurality of signal electrodes in a time sharing manner, and no selection signal is applied to other signal electrodes in the limited color display to allow only the filters, out of the color filters, in the form of stripes arranged to planarly overlap the signal electrodes respectively to which the selection signals are applied to be selected.
Further, in the present invention, when a display is performed on the liquid crystal display panel, a full color display of applying selection signals to the plurality of signal electrodes constituting all the pixel portions of the liquid crystal display panel in a time sharing manner, and applying data signals to the data electrodes in correspondence to the selection signals of the signal electrodes, and, further, at least one of the selection signal and data signal serving as a gradation signal for changing at many levels optical characteristics of the liquid crystal layer to allow the filters of three primary colors to be individually selected including gradations required for the full color display; and a reduced color display of reducing the number of levels of the gradation signal to be less than that of the full color display to allow the filters of three primary colors to be individually selected with the reduced gradation; are selectively performed.
In this event, it is suitable that a color reducing display of applying selection signals in such a manner to simultaneously select a plurality of the signal electrodes to simultaneously select the filters of a plurality of the colors arranged at positions corresponding to the plurality of signal electrodes, or a limited color display of applying selection signals to a part of the plurality of signal electrodes in a time sharing manner, and not applying selection signals to other signal electrodes to allow only the color filters arranged at positions corresponding to the signal electrodes to which the selection signals are applied to be selected, is also allowed to be selected.
Further, in the present invention, when in a color liquid crystal display panel including: a transparent first substrate formed with a plurality of signal electrodes and a transparent second substrate formed with a plurality of data electrodes arranged so that a face formed with the signal electrodes and a face formed with the data electrodes are opposed to each other; a liquid crystal layer sealed in a gap therebetween; pixel portions respectively constituted at portions where the signal electrodes cross over and planarly overlap the data electrodes; and color filters, in which filters of three primary colors in the form of stripes are alternately arranged to be parallel to and planarly overlap the data electrodes, provided on the first substrate or on the second substrate, a display is performed by selectively applying a voltage between the signal electrode and the opposed electrode to thereby change optical characteristics of the liquid crystal layer between the signal electrode and the opposed electrode at the pixel portion, the display is performed as follows.
A normal color display of applying selection signals to the plurality of signal electrodes constituting all the pixel portions of the color liquid crystal display panel in a time sharing manner, and applying data signals to the data electrodes in correspondence to the selection signals of the signal electrodes to allow the individual color filters of the pixel portions to be selected; and a color display of applying selection signals in such a manner to simultaneously select a plurality of the signal electrodes, and applying data signals to the plurality of data electrodes in a time sharing manner to allow the filters of a plurality of the colors in the form of stripes arranged to planarly overlap the plurality of data electrodes respectively to be individually selected and to reduce power consumption; are selectively performed.
Alternatively, a normal color display of applying selection signals to the plurality of the signal electrodes constituting all the pixel portions of the color liquid crystal display panel in a time sharing manner, and applying data signals to the data electrodes in correspondence to the selection signals of the signal electrodes to allow the filters of three primary colors in the form of stripes to be individually selected; and a black-and-white display of applying selection signals in such a manner to simultaneously select a plurality of the signal electrodes, and simultaneously applying the same data signals to three of the data electrodes on which the filters of three primary colors in the form of stripes are arranged to simultaneously select the filters of three primary colors to reduce power consumption; are selectively performed.
When the drive is performed by these methods, it is suitable that the normal color display or the full color display, and other display are switched according to time.
Further, it is suitable that the normal color display or the full color display, and other display are individually performed with a display region constituted by all the pixel portions of the color liquid crystal display panel divided into a plurality of display regions.
Furthermore, it is suitable that the normal color display or the full color display, and other display are switched according to a remaining capacity of a battery or a quantity of power generation by a power generator such as a solar cell or the like so that the normal color display or the full color display is performed when the remaining capacity of the battery or the quantity of power generation is larger than a predetermined capacity or quantity, and the other display is performed when the remaining capacity of the battery or the quantity of power generation is below the predetermined capacity or quantity.
Moreover, in the present invention, these methods are applied to a control of a display of a timepiece including a color liquid crystal display panel for displaying a time or information related to a time, wherein the color liquid crystal display panel is a liquid crystal display panel including: a transparent first substrate formed with a plurality of signal electrodes and a transparent second substrate formed with a plurality of data electrodes arranged so that a face formed with the signal electrodes and a face formed with the data electrodes are opposed to each other; a liquid crystal layer sealed in a gap therebetween; pixel portions respectively constituted at portions where the signal electrodes cross over and planarly overlap the data electrodes; and color filters, in which filters of three primary colors are alternately arranged at least at positions corresponding to the pixel portions, provided on the first substrate or on the second substrate, and displaying the time or information related to a time by selectively applying a voltage between the signal electrode and the opposed electrode to thereby change optical characteristics of the liquid crystal layer between the signal electrode and the opposed electrode at the pixel portion.